Regional differences in veins wall viscosity, compliance, energetics and damping: analysis of the pressure-diameter relationship during cyclical overloads.
BACKGROUND
The characterization of the dynamic process of veins walls is essential to understand venous functioning under normal and pathological conditions. However, little work has been done on dynamic venous properties.


OBJECTIVE
To characterize vein compliance (C), viscosity (eta), peak-strain (W St) and dissipated (W(D)) energy, damping (zeta), and their regional differences in order to evaluate their role in venous functioning during volume-pressure overloads.


METHODS
In a mock circulation, pressure (P) and diameter (D) of different veins (anterior cava, jugular and femoral; from 7 sheep), were registered during cyclical volume-pressure pulses. From the P-D relationship, C, W(St) and zeta (at low and high P-D levels), eta and W(D) were calculated.


RESULTS
For each vein there were P-dependent differences in biomechanical, energetics, and damping capability. There were regional-differences in C, eta), W(St) and W(D) (p<0.05), but not in zeta.


CONCLUSIONS
The regional-dependent differences in dynamics and energetics, and regional-similitude in damping could be important to ensure venous functioning during acute overloads. The lower C and higher W(St) and W(D) found in back-limb veins (femoral), commonly submitted to high volume-pressure loads (i.e. during walking), could be considered relevant to ensure adequate venous system functionality and venous wall protection simultaneously.
Zócalo
Yanina
Y
Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. yana@fmed.edu.uy
Bia
Daniel
D
Lluberas
Sebastián
S
Armentano
Ricardo L
RL
D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology*; D003187:Compliance; D005268:Femoral Vein / Q000033:anatomy & histology / Q000502:physiology*; D007601:Jugular Veins / Q000033:anatomy & histology / Q000502:physiology*; D012756:Sheep; D014682:Vena Cava, Inferior / Q000033:anatomy & histology / Q000502:physiology*; D014783:Viscosity